The Iranian president, Mahmoud Ahmadinejad, today rejected international demands for his country to suspend its uranium enrichment programme as a UN deadline to do so approached.

The UN security council has said Iran must cease its work on enrichment - a process in the manufacture of both nuclear fuel and material for nuclear weapons - by tomorrow or face further economic sanctions.

Tehran said that it wanted to resume negotiations over its nuclear ambitions, but Mr Ahmadinejad refused to stop its enrichment programme unless western countries did so too.

He told a crowd of thousands in northern Iran: "Justice demands that those who want to hold talks with us shut down their nuclear fuel cycle programme too. Then, we can hold dialogue under a fair atmosphere."

Speaking after the meeting, Mr Larijani warned the US against escalating the situation. "If they ... move into the boxing ring, they would have problems. But if they sit at the chess table, then both sides would come to a result," he said.

While saying his country was prepared to deliver "assurances that there would be no deviation ... toward a nuclear weapons programme", he offered no new suggestions. He said the key demand for Tehran to suspend enrichment was just a "pretext" to put political pressure on his country.

In an interview published today in the Financial Times, Mr ElBaradei said Iran could be as little as six months away from being able to enrich uranium on an industrial scale and that he did not expect Tehran to meet tomorrow's deadline.

The US and several of its western allies believe Iran is using its nuclear programme to produce an atomic weapon, but Tehran says its aim is to generate electricity.

Mr ElBaradei said in the FT interview that, according to US and British intelligence, Iran was still years away from developing a nuclear weapon.

But speculation has been growing that the US is drawing up contingency plans for an air strike against Iran's nuclear programme, despite repeated public denials by the Bush administration.

Last night, the BBC reported that a list of targets had been compiled and that air strikes would be triggered if US intelligence assessed that Tehran posed a "perceived nuclear threat" to the US or Iran was linked to a major attack on American forces in Iraq.

The US has put further pressure on Iran by sending a second aircraft carrier to the Gulf region. The John C Stennis and warships in its group arrived in the area yesterday.